In this competitive renewal of a highly successful grant investigating sociodemographic disparities in outcomes from systemic lupus erythematosus (SLE), including lupus nephritis and end-stage renal disease, we will turn our attention to the alarming and unexplained sociodemographic disparities that exist in SLE incidence. Most SLE patients are women and blacks have much higher incidence and poorer outcomes than whites. Moreover, within the population enrolled in Medicaid, the Federal-state insurance for low income Americans, we have shown increased SLE among those living in poorer areas. We will investigate three classes of potentially modifiable social and behavioral factors that may contribute to increased SLE incidence among black and low socioeconomic status women: 1. dietary factors and patterns, specifically fish (rich in anti-inflammatory omega-3 fatty acids), and the Western pro-inflammatory dietary pattern, characterized by fast food, high saturated fat, processed meats, potatoes, and sugar-sweetened soft drinks; 2. obesity, which induces systemic inflammation, and; 3. psychosocial factors including depressive symptoms, anxiety and exposure to abuse. We hypothesize that these exposures are associated with elevated biomarkers of SLE autoimmunity, as well as with incident SLE. We will utilize the largest collection of women followed prospectively prior to SLE, the Nurses' Health Study and the Black Women's Health Study cohorts, with rich data on dietary, lifestyle, psychosocial factors, and banked blood samples. With excellent statistical power, we will examine whether and how these exposures at different time periods of life may alter SLE risk among white and black women of a range of socioeconomic backgrounds. Our multidisciplinary investigative team spanning nutritional epidemiology, social and behavioral epidemiology, biostatistics, and rheumatology will employ advanced and innovative epidemiologic concepts and analyses. The proposed analyses will provide currently lacking information concerning potential epidemiologic explanations for observed sociodemographic disparities in SLE. The findings will have important public health and clinical implications, directly informing lifestyle interventions aimed at preventing and reducing disparities in SLE.